This application is a continuation of PCT International Application No.PCT/JP00/01997 filed Mar. 30, 2000.
The disclosures of the following priority applications are herein incorporated by reference: Japanese Patent Application No. 11-88797 Japanese Patent Application No. 11-88798 Japanese Patent Application No. 11-113794
1. Field of the Invention
The present invention relates to a working apparatus for construction machine and, more specifically, it relates to an working apparatus provided with an angle sensor that measures the relative rotating angles of members rotatably linked to each other such as the boom and the arm of a hydraulic shovel.
2. Related Art
In a construction machine such as a hydraulic shovel, an angle sensor is provided in the working apparatus. In such a working apparatus, the boom and the arm are linked with each other via a pin so as to allow them to rotate relative to each other, and their relative angles are detected by the angle sensor mounted at a side surface of the boom. The angle sensor, which comprises an input shaft, a sensor unit that detects the rotating angle of the input shaft and a case housing the input shaft and the sensor unit. The input shaft is linked or connected to the arm via a lever. When the arm is engaged in rotation relative to the pin, the input shaft at the angle sensor is caused to rotate via the lever which interlocks with the rotation of the arm. The rotating angle of the input shaft is detected by the sensor unit, and the relative angle of the arm is obtained based upon the detected value.
The angle sensor is mounted at the side surface of the boom so as to project out from the side surface, with one end of the lever linked to the input shaft of the angle sensor and the other end of the lever secured to a side surface of the arm. As a result, problems arise during operation in that the angle sensor and the lever projecting out to a side of the boom come into contact with soil and the like and that the angle sensor and the lever tend to interfere with objects in the vicinity.
These problems necessitate a large protective cover to be provided to protect the angle sensor from coming into contact with soil and the like. In addition, when soil or the like comes in contact with the lever, there is a risk of the angle sensor becoming damaged due to the impact to which the input shaft of the angle sensor is subjected via the lever.
An object of the present invention is to provide a working apparatus for construction machine that prevents the angle sensor provided at the boom or the like from becoming damaged readily by soil and the like.
In order to achieve the object described above, the working apparatus for construction machine according to the present invention comprises a first member, a second member rotatably linked with the first member via a linking member provided as an integrated part thereof and an angle sensor having an input shaft driven to rotate by the first member and a sensor unit that detects the rotating angle of the input shaft, and a recessed portion is formed at an end surface of the linking member along the axial direction thereof to house, at least, an angle sensor case in its entirety within the recessed portion.
Thus, the distance by which the angle sensor projects out from the end surface of the linking member along the axial direction thereof is reduced, thereby reducing the risk of falling soil or the like coming into contact with the angle sensor during operation. In particular, by housing the entire angle sensor inside the recessed portion, soil or the like is not allowed to come into contact with the angle sensor readily, and thus, the protective cover can be omitted.
In addition, a communicating member that links the first member and the input shaft so as to drive the input shaft to rotate by interlocking with the rotation of the first member is provided, (a) a recessed portion is formed at an end surface of the linking member along the axial direction to house the case in the recessed portion and (b) a projected portion projecting out along the axial direction of the input shaft is provided at an end surface of the case so as to enclose the input shaft outside of the movement range of the communicating member. By forming such a projected portion, it is ensured that the input shaft is protected by the projected portion even when soil, rocks and the like come falling down.
Furthermore, by projecting the projected portion of the case out from the end surface thereof along the axial direction further than the distance over which the input shaft projects out, an improvement is achieved in the protective function of the projected portion in protecting the input shaft. By providing an input shaft protective cover, a further improvement is achieved in the degree of protection provided for the input shaft, and also, by securing the input shaft protective cover and the angle sensor to the linking member with a common fastener, the number of required parts can be reduced.
By forming a passage for a wiring harness in the angle sensor case, the wiring harness can be drawn out of the recessed portion from the sensor unit with ease. Alternatively, it is acceptable to provide a seal member that seals the external circumferential surface of the case and the internal circumferential surface of the recessed portion at the external circumferential surface, a groove formed at the external circumferential surface of the case and a passage for the wiring harness formed at the seal member at a position aligned with the position of the groove.
Moreover, by providing a communicating member linking the first member and the input shaft and allowing the link between the first member and the input shaft to become released when an external force equal to or exceeding a specific level is applied to the communicating member, it is possible to ensure that no excessive impact force is applied to the input shaft of the angle sensor, thereby increasing the service life of the angle sensor. For instance, the link may be released by allowing the end of the communicating member slidably inserted in a hole at the input shaft to slip out of the hole or by causing the communicating member to break, when an external force equal to or exceeding the specific level is applied.